1. Field of the Invention
The present invention relates to a facsimile apparatus, and more particularly to the facsimile apparatus which includes a data terminal device and a facsimile modem device.
2. Description of the Related Art
In general, a facsimile system is so arranged that a facsimile apparatus for transmitting a still picture communicates with another facsimile apparatus for receiving the transmitted still picture through a communication path.
The still picture includes a certain amount of information (characters, digits, diagrams, etc.) on a definitive area. As for the characters included in the still picture, the most important feature in transmitting the still picture is a reproduction fidelity of the most fine characters on the receiving-side facsimile.
The indispensable factors of the facsimile apparatus are to reproduce the character style and to discern clearly the characters from one another. In order to cooperate the indispensable factors, in general, the facsimile apparatus is arranged to code the still picture in binary digits of black and white at a time when the picture information is extracted, transmitted and reproduced.
The inventors of the present invention know that there is a facsimile apparatus having a data terminal device and a facsimile modem device, both of which are connected through a serial data line so that the data is allowed to be serially transmitted therebetween. The facsimile modem device is also connected with a phone line.
The data terminal device is a terminal apparatus represented by a personal computer or a wordprocessor and includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a communication control unit, an I/O control unit, an image reading device and a keyboard.
The CPU is used to control and to monitor the data terminal device itself. The ROM, the RAM, the communication control unit and the I/O control unit are connected to the CPU so that the data is transmitted between the CPU and those elements.
The facsimile modem device includes a CPU, a ROM, a RAM, a modem LSI and a network control unit (NCU). The CPU is connected to the ROM, the RAM, and the modem LSI through a system bus so that the data is allowed to be transmitted between the CPU and the other elements as fast as possible.
The CPU is used to control and to monitor the facsimile modem device.
In operation, the data terminal device takes the following steps consisting of a step of reading one-line data contained in a subject copy (that is, one sheet of paper to be facsimile-transmitted) from the RAM, a step of expanding the read data into a bit image in the CPU in a case of the character data, a step of storing the bit image in the RAM, a step of compressing the bit-image data read from the RAM into the transmission data format, a step of transmitting the compressed data to the facsimile modem device through the communication control unit, a step of determining whether or not all the lines of the one-copy data (corresponding to the data of one sheet of paper to be transmitted) are transmitted.
When all the lines of the one-copy data are transmitted it proceeds to a step of transmitting a message indicating termination of the processing of one subject copy to the facsimile modem device.
However, when not all the lines of the one-copy data are transmitted, then it proceeds to a step of returning to the first step.
In a case that the data to be transmitted is image data optically scanned by the image reading device, the above-mentioned step of expanding the read data into a bit image is not necessary.
The facsimile modem device takes the following steps consisting of a step of storing the compressed data transmitted from the data terminal device in the RAM, a step of reading the data from the RAM under the control of the CPU, a step of transmitting it to the modem LSI, a step of modulating the data in the LSI, a step of transmitting the modulated data to the phone line through the network control unit which keeps the transmission characteristic optimal, a step of determining whether or not all lines contained in one-copy data are transmitted.
When all lines contained in one-copy data are transmitted, then it proceeds to a step of terminating the process.
However, when not all lines contained in one-copy data are transmitted, then it proceeds to a step of returning to the first step of storing the transmitted data in the RAM.
As will be understood from the above description, for transmitting the character data with the facisimile, the above-mentioned facsimile apparatus takes a step of quantizing (expanding) the character data into the image data (bit-image data) on the data terminal device, a step of coding (compressing) the image data for enabling facsimile transmission, and a step of transmitting the coded character data to the facsimile modem device.
Hence, it takes a considerably long time to execute the series of processes from the coding of the data to the transfer of the coded data to the facsimile modem device, resulting that a time is substantially consumed in order to carry out the facsimile transmission.
In a case that the image data is to be transmitted, the process of expanding the image data in the data terminal device is removed.
However, it is necessary to code (compress) the image data so that the data is allowed to be transmitted with the facsimile, resulting that a time is disadvantageously consumed in order to code the image data and to transfer the data from the data terminal device to the facsimile modem device.
Moreover, when the facsimile modem device is allowed to be connected to a data terminal device included in another facsimile apparatus, the data terminal device to be connected is indispensable to the provision of expansion of the data into the bit image and compression of the data into a data transmission format as well as an addition of a special function of enabling the compressed data to be transferred to the facsimile modem device of another facsimile apparatus, resulting that a freedom is constrained too much in the arrangement of the facsimile apparatus itself.